兰新铁路第二双线大单元双块式无砟轨道温度效应理论分析

Theoretical Analysis on Temperature Effect of Large Unit Double-block Ballastless Track for Lanzhou-Xinjiang Second Double-track Railway

采用大单元双块式无砟轨道结构的兰新(兰州—乌鲁木齐)铁路第二双线位于西北大温差地区,温度荷载是影响其服役性能的重要因素。本文建立了长度为19.5 m的大单元板有限元模型,对降温荷载作用下轨道结构的开裂形式和升温荷载作用下轨道结构失稳的可能性进行了模拟和分析。结果表明:开裂成5块小单元板是大单元板受降温荷载作用开裂后的稳定形态;升温荷载将使小单元板间距缩小但不会导致其发生挤压破坏或失稳;道床板内的纵向钢筋对假缝处裂缝宽度的变化有明显抑制作用。

Lanzhou-Xinjiang second double-track railway using large unit double-block ballastless track structure is located in the northwest region with large temperature variation,which means the temperature load is an important factor affecting the service performance of ballastless track.A finite element model of large unit double-block ballastless track slab with 19.5 m length was established in this paper to simulate and analyze the crack form of track structure under the action of cooling load and the instability possibility of track structure under the action of heating load respectively.The results show that 5 small unit track slabs are the stable form after cracking of the large unit track slab under the action of cooling load,the heating load reduces the gap between small unit track slabs which could not lead to the extrusion failure or instability,and longitudinal reinforcing steel bar inside track slabs has a significant inhibitory effect on the changes of pre-splitting crack width.